Commutator tube



Oct. 18, 1955 H. P. KNAUSS 2,721,286

COMMUTATOR TUBE Filed Aug. 5, 1948 3 Shee tsSheet l FVGE/ MI/E/VTOIF 1919 9010 f? XIV/9055' Oct. 18, 1955 H. P. KNAUSS 2,721,286

COMMUTATOR TUBE Filed Aug. 5, 1948 3 Sheets-Sheet 2 INVENTOR HAROLD P KNAUSS A TORNEV United States Patent O COMMUTATOR TUBE Harold P. Knauss, Dayton, Ohio, assignor to Raytheon Manufacturing Company, a corporation of Delaware Application August 5, 1948, Serial No. 42,589

19 Claims. (21. 31369) This invention relates to electron tube devices for commutation of electric currents in successive difierent circuits, and in particular to an improved commutator tube having amplifying as well as commutating characteristics.

In copending application Serial No. 655,447, filed March 19, 1946, now U. S. Patent No. 2,684,449 granted July 20, 1954, there is disclosed a commutator tube employing a cathode, an electron accelerator electrode surrounding the cathode, and a plurality of electron collectors arranged in commutator fashion closely about the accelerator electrode, on the outside thereof. The'electrons emitted by the cathode are formed into a beam which is swept along the accelerator electrode. The accelerator electrode has an aperture which is elongated in the direction in which the beam sweeps. .The beam passes through this aperture and impinges on one or more of the collector electrodes, sweeping across them in succession, thereby electrically connecting the cathode with successive ones of said collector electrodes. As is. explained in said copending application, the operation of the tube is such that the electrons of the beam substantially lose their velocity in the region between the accelerator and commutator electrodes, so that a virtual cathode exists in that region, which virtual cathode is made available to successive commutator electrodes by rotation of the beam about the true cathode. This tube operates electrically as a commutator switch, and hence does not isolate the input and output circuits. As an electron tube, it is a diode, and consequently has no ability to amplify the signal that is being commutated.

It is the primary object of the presentinvention to provide a commutator type electron tube wherein the gain can be varied as desired.

It is another object of the invention to provide such a tube which can be employed to isolate the input and output circuits.

It is another object to provide such a commutator tube which performs at least as well as the aforementioned diode types as far as the commutating function is concerned, namely, which commutates swiftly and smoothly and with a minimum of commutation noise at high commutation speeds.

It is another object to provide such a commutation tube which is structurally strong and rugged, and is constructed with a minimum of complexity. 7

It is another object to provide such a tube which will be of convenient size and not unduly large or clumsy to handle.

Other and further objects and features of the invention will become apparent from the detailed discussion of an embodiment thereof that follows, reference being made to the accompanying drawings, wherein:

Fig. 1 is a side elevation partly in section of a commutator tube constructed in accordance with the inven-' tion;

Fig. 1A is a top view of Fig. 1 on a reduced scale showing the beam-forming and tilting means;

2,721,286 Patented Oct. 18, 1955 Fig. 2 is a bottom view of the tube of Fig. 1, with the beam deflection means omitted;

Fig. 3 is a detail showing the commutating grid con struction;

Fig. 4 is a diagrammatic View showing the cooperation between the cathode beam and the commutating grids;

Fig. 5 is an electrical schematic diagram showing the tube of the invention in a utilization circuit; and

Fig. 6 is a simplified electrical schematic diagram showing the tube in another utilization circuit.

Referring now to Fig. 1, a tube 10 in accordance with the invention is shown about one and one-half times actual size. The essential elements of the tube are an electron-emissive cathode 11, a pair of equi-diameter cylindrical electron accelerator electrodes 12 and 13 sur' rounding the cathode and spaced axially apart to provide a circumferentially uninterrupted passage 14 therethrough for the passage of electrons, a plurality of generally axially disposed control grid wires 15 surrounding the accelerator electrodes 12 and 13, a pair of equi-diameter cylindrical screen electrodes 16 and 17 surrounding the grid wires 15 and spaced axially apart to provide a second circumferentially uninterrupted passage 18 therethrough, and a cylindrical anode 19 surrounding the screen electrodes. The entire assembly is supported on top and bottom plates 21 and 22, respectively, of mica or the like, an enclosed in an envelope 23, suitable for evacuation. The top and bottom plates are attached to opposite axial ends of the anode 19. The screen electrodes 16 and 17 are mounted on the inner sides of the top and bottom plates 21 and 22, respectively, concentric with the anode. Two circular insulating plates 24 and 25, of mica or the like, having like diameters less than the inner diameter of the screen electrodes but greater than the outer diameter of the accelerator electrodes, are mounted concentrically on the inner sides of the top and bottom plates 21 and 22, respectively, spaced therefrom by spacers 26 suitably distributed. The top and bottom accelerator electrodes 12 and 13 are mounted on these inner plates 24 and 25, respectively.

An annulus 27 or 28, of a rigid non-conductive material, such as a ceramic, is mounted on the outside of each accelerator electrode 12 or 13, respectively. The inner diameter of each annulus is such that the annulus fits snugly on the acceleratorelectrode'cylinderl Each annulus is of substantial thickness in the axial direction, for example, about one-eighth inch, and is provided with a plurality of axially directed V-shaped grooves'30 (Fig. 3) equally spaced around the outer circumference thereof. The grid wires 15 are tightly stretched between these two annuli 27 and 28, each wire being fastened at each end in a groove 30. In the tube shown in Fig. 1, there are 288 grid wires 15, and hence 288 grooves 30 on each annulus. The grooves are conveniently V-cut at an angle of 60 degrees. For purposes to be hereinafter described, the grid wires 15 are directedlnearly but not quite parallel to the tube axis, namely, the axis of the other concentric elements, but are slightlyskewed with respect thereto. The effect is the same as though the grid wires were all mounted parallel to the axis, and then one annulus rotated with respect to the other about the tube axis.

The cathode 11 is of the coated type, and is mounted in the inner plates 24 and 25, on the tube axis. For reasons that will appear below, it is desired that the cathode shall be of restricted length, yet, when the emissive material that is usually employed to coat the cathode metal is applied, it extends beyond the desired limits. To prevent the supporting ends of the cathode from emitting electrons, theyare covered with close fitting electrically conductive shields 31 and 32, which are flared out at the ends near the emissive cathode 11. The'shields 31 and 32 prevent the emission from the extra material from leaving the cathode. The cathode is preferably indirectly heated, in a well-known manner (not shown).

The entire assembly of tube elements is supported on electrically conductive rods 33, 34, 35, 36, 37, and 38. The two outer rods 33 and 38 are fastened. as by welding, to the anode 19 at diametrically opposed points; the next outermost pair of rods 34 and 37 are similarly fastened to the lower screen electrode 17; and the innermost pair of rods 35 and 36 are similarly fastened to the lower accelerator electrode 13, respectively. A stabilizing rod 39' is fastened between the innermost two rods 35 and 36, at points a substantial distance from the electrodeassembly. While the various pairs of rods that are fastened to the different electrodes are shown lying on the same diameter in Fig. 1, it will be appreciated that they can, and they preferably will, lie on different diameters. The upper screen electrode 16 is provided with an electrical connection lug 41 extending through the top outer supportingplate 21, and is electrically connected to the lower screen electrode 17 by a wire 42 connected between this lug and one of the rods 34 connected to the lower electrode. The upper accelerator electrode 12 is provided with an electrical connection lug 43 extending through both the inner and the outer top supporting plates 24' and 21, respectively, and is connected to the lower accelerator electrode 13 by a wire 44 connected between this lug and one of the rods 36 connected to the lower accelerator electrodes. The cathode is provided with a pair of connecting wires 45 and 46 to the heater (not shown) and a single connecting wire 47 to the heated element. The grid wires are provided with connecting. wires 48, of which each is connected to six adjacent grid wires 15, so that the 288 grid wires actually constitute 48 diiferent grids, each made of six individual wires. This construction is shown more clearly in Fig. 4.

The envelope 23 is made preferably of glass in twoparts, of which the upper 51 is the larger and contains the tube element assembly and the supporting and connecting conductors. The lower portion 52 completes the envelope, and is provided with an extension 53 through which the envelope is exhausted, and which is then sealed 01f. Each envelope portion is thickened at the rim 54, 55 of its mouth and it is at these thickened rims that the two portions are sealed together to form the completed envelope. When the rims are sealed together, they form a thickened annulus in which all the electrical connection terminals of the tube are sealed. As shown in Fig. 2, the terminals 56 all project radially from the thickened annulus. Each terminal 56 is an elongated rigid. rod which projects radially into the envelope 23 a suflicient distance to meet the axially disposed conductor to which it is to be connected, as shown at 57'. The terminal rods 56 are thus each disposed at right angles'to the wires 48, 47, 46 and 45, and the supporting conductors 33 to 38, inclusive, to which they are connected. Being rigid, the terminal rods 56 that are connected to the wires 45 to 48, inclusive, serve to hold those wires taut while the remaining terminal rods serve to support the electrode assembly in the envelope.

The electrons emitted by the cathode 11 are formed into a pair of oppositely directed beams 61 and 62, by suitable magnetic means having two opposite poles N and S, disposed closely outside the tube envelope on diametrically opposite sides of the electrode assembly. The magnetic poles are rotated about the tube axis to operate the tube as a commutator. The rotatable magnetic field can be provided in any convenient manner. In the illustrated embodiment, a tetrapolar electromagnetic resolver 64, shown in Fig. 1A, having a coil 65, 66, 67, and 68 for each of its four poles, provides the rotatable magnetic field when the four coils are energized by sinusoidal voltages in phase quadrature, as iswellknown. The poles of the resolver are uniformly distributed about the circumference of the tube 10. The

beams 61 and 62 are tilted with respect to the tube axis, so that one beam 61 passes through the annular passages 14 and 18 and reaches the anode 19, while the oppositely directed beam 62 is interrupted by the material of the lower accelerator electrode 13. To this end the cathode 11 is disposed partially below the general plane of the first or inner annular passage 14 and completely below the general plane of the second or outer annular passage 18. The outer passage 18 is to this end axially displaced toward the top of the tube 10 with respect to the inner passage 14. An electromagnetic field for tilting the beam toward parallelism with the tube axis is provided by a solenoidal coil 69, which may be wound closely on the envelope 23 near the electrode assembly as shown, or disposed in any other convenient location. This coil provides a magnetic field parallel to the tube axis when energized with direct current. The feature of tilting the beam is described and claimed in detail in copending application Serial No. 787,441, filed November 21, 1947, now Patent No. 2,654,040, dated September 29, 1953.

During operation of the tube, the beam 61, which is employed for commutation, sweeps by successive grid wires 15; The cross-sectional shape of the beam is generally rectangular, due to the rectangular shape of the cathode 11 when viewed along the beam axis. The focussing magnetic field does not change this shape appreciably. Further, the annular apertures 14 and 18 are both of sufficient width so that the beam can pass through substantially without any of the beam electrons impinging upon the electrode metal. This contributes to quiet operation of the tube. As in the case of the diode type tube mentioned above, a virtual cathode 63 is formed onthe outer side of the accelerator electrode aperture 14. This comes about as follows.

The cathode 11 emits electrons when heated. These electrons have kinetic energy and readily leave the cathode, so that soon an electron cloud is formed in the immediate vicinity of the cathode. The accelerator electrodes 12 and 13 are provided with a positive charge with relation to the cathode, for example, about 20 volts, which charge accelerates electrons from the cloud toward the aperture 14. Due tothe focussing effect of the magnetic field, none or at most very few of the accelerated electrons are directed from the beam toward the electrodes 12 and 13. After passing. through the aperture 14, the electrons lose velocity, for they are still under the influence of the accelerator electrodes 12 and 13. As a result the electrons in the beam beginto bunchtogether in the region between the accelerator electrode aperture 14 and the grid wires 15.

Electrons which approach the bunch 63 at lower than average velocity are repelled thereby, and turn back toward the accelerator electrodes 12 and 13. Since such electrons are moving very slowly, they are easily attracted by one or the other of the accelerator electrodes, and removed from the scene;

ageof the cathode: near certain ones of the grids, in other words, a' virtual cathode 63. This virtual cathode is caused to move in a circular path as the beam 61 rotates,

thereby becoming available to successive groups of grid wires.- The tube 10can therefore be thought of as a group of 48 potential triode tubes or the like, each lacking a cathode which is provided successively to one after the other of them.

The average velocity of the electrons in the virtualcathode 63 is such that the virtual cathode is at a potential level of approximately one volt with respect to the actual or real cathode. The grid wires 15 are placed very close to the virtual cathode and operated at the same potential level. The anode 19 is placed a suitable distance away and operated at. apotentiallevel of about 300 volts. There is accordingly at all times a flow of electrons from the virtual. cathode to the anode, or, in other words, the beam 61 is not cut ofi; the electrons therein are slowed down close to the grid wires to provide the virtual cathode and The electrons in the bunch are thus kept sharply in focus, and constitute in etfect an im then electrons drawn from the virtual cathode are accelerated toward the anode. However, the virtual cathode 63 and the grid wires 15 can be placed very close together; in fact they could, if desired, be made to occupy the same space, so that the grid wires can exercise great control over the electron flow to the anode with very small changes in potential.

The screen electrodes 16 and 17 are maintained at the potential of the real cathode 11, and serve to isolate the gridwires 15 electrostatically from the anode 19.

It Will be seen from Fig. 1 that the accelerator electrodes 12 and 13 are spaced relatively a large distance from the real cathode 11, while the grid wires 15 and anode 19 are much closer together. As has already been stated, the virtual cathode 63 is very close to the grid wires 15. The tube can now be seen to have another advantage. Since the structure illustrated provides a virtual cathode anywhere on a circle of large radius as compared to the real cathode, there is room to surround the virtual cathode circle with a large number, here 288, grid wires. Of course, if the number of grid wires to be employed, that is the number of signals to be commutated, is small, the radius of the virtual cathode circle can be reduced accordingly. This would be done by reducing the diameter of the accelerator electrodes 12 and 13. I

The characteristics of the tube have been found to be such that, with the aforementioned operating potential values, the plate current changes rapidly with small changes in grid potential about a median level of the order of one volt with respect to the cathode. Above this region, the plate current becomes substantially constant with increasing grid potential, until the grid potential is increased to a value where the grid begins to draw current. Above this value of grid potential, the plate current is diminished by the amount taken by the grid.

To make certain that the beam 61 establishes and gives up contact with individual grid wires in a gradual manner, the grid wires are skewed with respect to the tube axis, as illustrated in Fig. 4. The beam is represented by a rectangular shaded block, moving to the left. The beam is just beginning to make contact with one wire 15a and to give up contact with another wire 15b. The skew angle of the grid wires is preferably such that the top corner of the leading or left-hand edge of the beam rectangle just touches one wire 15c at the same time that the bottom left corner just touches the next adjacent wire 15a. Thus the leading edge of the beam is constantly establishing new contact with the same amount of grid wire 15, and commutator noise is held to a minimum. The same is true of the trailing, or right-hand, edge of the beam. Since each commutating grid connector 48 includes six grid wires 15, the change from one commutator position to the next can be made very smooth, gradual, and devoid of commutator noise, even in very high speed commutator circuits.

The tube 10 is shown in a utilization circuit in Fig. 5. The cathode lead 47 is grounded at 71. A battery 72 furnishes about 20 volts positive bias to the accelerator electrodes 12 and 13. This battery is connected at its positive terminal to the accelerator grid connection lead 36 and at its negative terminal to the cathode, or ground 71. A by-pass capacitor 73 is connected across the battery 72. The screen electrodes 16 and 17 are connected to ground via their common connecting lead 34. Signals which are to be commutated are provided to the grid wires 15 by individual signal generators G1, G2, G3, each of which is connected at one side to a separate grid lead 48 via a separate coupling capacitor 75, 76, 77, respectively, and at the other side to ground. It will be appreciated, of course, that 48 separate signals can be commutated with the tube 10 that is illustrated, and that the three signal generators that are shown are symbolic of all 48 signals. The signals themselves can come from any source, for example, an array of sound transducers or antennae wherein each individual signal P represents a difierent member or a different directivity of the array. A system of under-water sound transducers wherein the present invention may be employed to advantage is described and claimed in copending application Serial No. 14,017, filed March 10, 1948. A signal coupling resistor 81, 82, 83 is connected from the grid lead 48 of each signal generator G1, G2, or G3, respectively, to a common junction 84 for all the coupling resistors. A grid bias battery 85 is connected between the common junction and ground 71, the positive terminal of the battery being connected to the common junction. The battery 85 furnishes the grid wires 15 with a small bias of about one volt positive with respect to the cath ode 11. The anode 19 is provided with about 300 volts positive unidirectional potential with respect to the cathode by a battery 88 through a load resistor 89. The bat tery 88 is connected to ground 71 at its negative terminal and at its positive terminal to the resistor 89, which is in turn connected to the anode lead 33. A by-pass capacitor 91 is connected across the battery 88. 'The' commutated signal is coupled to succeeding stages via a coupling capacitor 92.

The plate-to-cathode resistance of the tubeis of the order of several megohms. The plate circuit load resistor 89 may preferably be any value between 10,000 ohms and one megohm, although othervalues may be used if desired. It will be appreciated that the batteries 72, 85, and 88 are symoblic of any and all the usual and well-known systems for providing tube electrode potentials. The utilization circuit of Fig. 5 provides any desired value of gain from 0.1 to 5.0, depending on the circuit constants and electrode potentials that are chosen.

If it is desired to isolate the stages that follow the commutator tube from the signal input circuits, the tube can be employed in a cathode follower circuit, as shown in Fig. 6. In this figure, the tube 10 is represented symbolically, showing only the beam 61 that is being used. The other electrodes in the tube are all shown to one side of the cathode, and only one generator G1 is illustrated; as this much is all that needs to be shown to illustrate the cathode-follower circuit connections. The accelerator electrode bias battery 72 is connected between the cathode 11 and the accelerator electrodes 12, 13. and a load impedance 95 is connected between the oath ode and ground 71. The input signal is connected be-- tween the grid 15 and ground, the steady-state positive bias of about one volt being retained. The anode 19 is furnished with anode potential directly, there being no impedance element in the anode-to-potentialsupply connection. The output is taken across the load impedance element 95,;via. acoiipling condenser 96.

The impedance element 89 or may take any desired form. It may be attuned circuit, for example, a parallel-tuned circuit resonant to the generator frequency, or it may simply be a resistor. The former is useful when all the signals being commutated are of or close to the same frequency, while the latter is useful when the commutated signals are of different frequencies.

The electrodes 12, 13, 15, 16, 17, and 19 and their connecting leads may be of any suitable non-magneti material.

Various other forms of the invention will occur to those skilled in the art. Accordingly, it is intended that the claims that follow shall not be limited to the details of the foregoing description, but only by the prior art.

I claim:

1. An electronic commutator tube device comprising: a soure of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a prescribed path; a plurality of individual control electrodes disposed in a line parallel to said prescribed path, between said source and said anode; and electrode means disposed between said anode and said source to cause substantial bunching of the beam electrons in the vicinity of .said control electrodes.

2. An electronic commutator tube device comprising: a source of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a prescribed path; an electronaccelerator electrode disposed between said source and said anode, said accelerator electrode having a continuous elongated aperture extending parallel to said prescribed path and positioned inthe line of travel of electrons in said beam; and a plurality of individual control electrodes disposed between said source and said anode in a line parralel to said prescribed path.

3. An electronic commutator tube device comprising: a source of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a prescribed path; an electronaccelerator electrode disposed between said source and said anode, and having a first continuous elongated aperture; a screen electrode disposed between said accelerator electrode and said anode, and having a second continuous elongated aperture; both of said apertures extending parallel to said prescribed path and positioned in the line of travel of electrons in said beam; and a plurality of individual control electrodes disposed between said source and said anode in a line parallel to said prescribed path.

4. An electronic commutator tube device comprising: a source of electrons; an electron-accelerating electrode positioned near said source, said electrode having a continuous elongated aperture; an anode positioned near said electrode, on the opposite side thereof from said source, and extending in the same direction as said aperture; a plurality of individual control electrodes arrayed between said accelerator electrode and said anode in said same direction; means adjacent said tube device for forming electrons from said source into a beam extending from said source through said aperture toward said anode; and means adjacent said tube device for sweeping said beam angularly about said source in said same direction.

5. An electronic commutator tube device comprising: a source of electrons; an electron-accelerating electrode positioned near said source, said electrode having a continuous elongated aperture; an anode positioned near said electrode, on the opposite side thereof from said source, and extending in the same direction as said aperture; a plurality of individual control electrodes arrayed between said accelerator electrode and said anode in said same direction; a screen electrode positioned between said control electrodes and said anode, said screen electrode having a second continuous elongated aperture extending in said same direction; means adjacent said tube device for forming electrons from said source into a beam extending from said source through both of said apertures toward said anode; and means adjacent said tube device for sweeping said beam angularly about said source in said same direction.

6. An electronic commutator tube device comprising: a source of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending along a first line between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a path perpendicular to said first line; and a plurality of parallel control grid wires arrayed in a second line parallel to said path, said wires being individually disposed in a direction which is inclined in the direction of said path with respect to a third line mutually perpendicular to said first and second lines.

7. An electronic commutator tube device comprising: a source of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending along a first line between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a path perpendicular to said first line; and a plurality of parallel control grid wires arrayed in a second line parallel to said path, said wires being individually disposed in a direction which is inclined in the direction of said path with respect to a third line mutually perpendicular to said first and second lines, and making a small angle with said third line.

8. An electronic commutator tube device comprising: a source of electrons; an anode; means adjacent said tube device for forming electrons from said source into a beam extending between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source, whereby the anode end of said beam traverses said anode in a prescribed path; a plurality of individual control electrodes uniformly arrayed parallel to said prescribed path, between said source and said anode; and electrode means disposed between said anode and said source to cause substantial bunching of the beam electrons in the vicinity of said control electrodes.

9. An electronic commutator tube device comprising: a source of electrons; an anode surrounding said source; means adjacent said tube device for forming electrons from said source into a beam extending between said source and said anode; means adjacent said tube device for sweeping said beam angularly about said source; a plurality of individual control electrodes surrounding said source, between said source and said anode; and electrode means disposed between said anode and said source to cause substantial bunching of the beam electrons in the vicinity of said control electrodes.

10. An electronic commutator tube device comprising: a source of electrons, an accelerator electrode surrounding said source, and having a continuous circumferentially directed aperture therein; an anode surrounding said accelerator electrode; means adjacent said tube device for forming electrons from said source into a beam extending from said source to said anode through said aperture; means adjacent said tube device for sweeping said beam angularly about said source; and a plurality of individual control electrodes surrounding said source, between said source and said anode.

11. An electronic commutator tube device comprising: a source of electrons; an accelerator electrode surrounding said source, and having a first continuous circumferentially directed aperture therein; a screen electrode surrounding said accelerator electrode and having a second circumferentially directed aperture therein; an anode surrounding said screen electrode; means adjacent said tube device for forming electrons from said source into a beam extending from said source to said anode through both of said apertures; means adjacent said tube device for sweeping said beam angularly about said source; and a plurality of individual control electrodes surrounding said source, between said source and said anode.

12. An electronic commutator tube device comprising: a source of electrons; an accelerator electrode surrounding said source, and having a first continuous circumferentially directed aperture therein; a screen electrode surrounding said accelerator electrode and having a second circumferentially directed aperture therein; an anode surrounding said screen electrodes; means adjacent said tube device for forming electrons from said source into a beam extending from said source to said anode through both of said apertures; means adjacent said tube device for sweeping said beam angularly about said source; and a plurality of individual control electrodes surrounding said source, between said accelerator electrode and said screen electrode.

13. An electronic commutator tube device comprising: a source of electrons; an anode surrounding said source; means adjacent said tube device for forming electrons from said source into two beams extending in opposite directions between said source and said anode; means adjacent said tube device for sweeping said beams angularly about said source; a plurality of individual control electrodes surrounding said source, between said source and said anode; electrode means surrounding said source between said source and said anode to cause substantial bunching of the beam electrons in the vicinity of said control electrodes; and means for suppressing one of said beams.

14. An electronic commutator tube device comprising: a cylindrical anode; a cathode positioned substantially on the axis of said anode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode; means adjacent said tube device for sweeping said beam angularly about said cathode; a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentrically within said anode; and electrode means between said anode and said cathode to cause substantial bunching of the electrons of said beam in the vicinity of said grid wires.

15. An electronic commutator tube device comprising: a cylindrical anode; a cathode positioned substantially on the axis of said anode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode; means adjacent said tube device for sweeping said beam angularly about said cathode; a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentrically within said anode, said grid wires being mutually parallel and uniformly spaced apart on said circle; and electrode means between said anode and said cathode to cause substantial bunching of the electrons of said beamin the vicinity of said grid wires.

16. An electronic commutator tube device comprising:

a cylindrical anode; a cathode positioned substantially on the axis of said anode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode; means adjacent said tube device for sweeping said beam angularly about said cathode; a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentrically within said anode, said grid wires being mutually parallel and circumferentially skewed from one end of each wire to the other; and electrode means between said anode and said cathode to cause substantial bunching of the electrons of said beam in the vicinity of said grid wires.

17. An electronic commutator tube device comprising: a cylindrical anode; a cathode positioned substantially on the axis of said anode; a cylindrical electron-accelerator electrode having a continuous circumferential aperture positioned concentrically within said anode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode through said aperture; means adjacent said tube device for sweeping said beam angularly about said cathode; and a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentric within said anode.

18. An electronic commutator tube device comprising: a cylindrical anode; a cathode positioned substantially on the axis of said anode; a cylindrical electron-accelerator electrode having a continuous circumferential aperture positioned concentrically within said anode; a cylindrical screen electrode having a second continuous circumferential aperture positioned concentrically within said anode and surrounding said accelerator electrode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode through both of said apertures; means adjacent said tube device for sweeping said beam angularly about said cathode; and a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentric within said anode.

19. An electronic commutator tube device comprising: a cylindrical anode; a cathode positioned substantially on the axis of said anode; a cylindrical electron-accelerator electrode having a continuous circumferential aperture positioned concentrically within said anode; a cylindrical screen electrode having a second continuous circumferential aperture positioned concentrically within said anode and surrounding said accelerator electrode; means adjacent said tube device for forming electrons from said cathode into a beam extending toward said anode through both of said apertures; means adjacent said tube device for sweeping said beam angularly about said cathode; and a plurality of generally axially directed control grid wires arrayed about said cathode in a circle concentric with and between said accelerator and screen electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 2,217,774 Skellett Oct. 15, 1940 2,390,884 Jansky Dec. 11, 1945 2,391,967 Hecht et a1 Jan. 1, 1946 2,440,639 Marmont Apr. 27, 1948 2,645,741 Westervelt July 14, 1953 

